Performing tasks using a virtual desktop environment has become common. An advantage of the virtual desktop environment is that a user can use the same environment using any access client. Hence, the user can move from his/her office to a distant office without carrying a terminal and perform tasks using an access client belonging to the distant office.
In the prior art, however, virtual machines (VMs) are disposed in a single data center (DC), and there is a problem with the performance of a response from an access client to a VM when a user is distant from the DC. Accordingly, in accordance with the user's movement, the VM is transferred to a DC close to the user. To do this, a file system (FS) is shared between DCs distant from each other, so that an image file (VM image file) stored in a storage apparatus belonging to a VM can be accessed from any of the DCs. In particular, an FS distributed among DCs is used. An image file is generated by compiling a plurality of pieces of data stored in a storage apparatus. A VM is executed using a VM image file.
Data is frequently written to a VM image file while a VM is in operation. However, for the conventional distributed FS, communications are frequently performed between servers that form a cluster, so as to maintain integrity in writing data. Hence, when the conventional distributed FSs, for which long distances between servers are not considered, are distributed among DCs, it is difficult to achieve a practical performance for a response from an access client to a VM.
In a well-known distributed file system, a file catalog stored by a master server is accessed; routing information of a meta server associated with a file to be accessed is obtained from the master server; the meta server is accessed according to the routing information; the meta information of the file to be accessed is obtained from the meta server; and the file to be accessed is accessed from a plurality of node servers (see, for example, patent document 1).
While a VM image file is being transferred to transfer a VM between DCs, the operation of the VM is stopped.
Patent Document 1: Japanese National Publication of International Patent Application No. 2015-528957
Patent Document 2: Japanese Laid-open Patent Publication No. 2013-93050
Patent Document 3: Japanese National Publication, of International Patent Application No. 2014-503086